Current regulations require that all cardiac allograft offers for transplantation must include an interpreted 12-lead electrocardiogram (ECG). However, little is known about the expected ECG findings in potential organ donors or the clinical significance of any identified abnormalities in terms of cardiac allograft function and suitability for transplantation.A single experienced reviewer interpreted the first ECG obtained after brain stem herniation in 980 potential organ donors managed by the California Transplant Donor Network from 2002 to 2007. ECG abnormalities were summarized, and associations between specific ECG findings and cardiac allograft use for transplantation were studied. ECG abnormalities were present in 51% of all cases reviewed. The most common abnormalities included voltage criteria for left ventricular hypertrophy, prolongation of the corrected QT interval, and repolarization changes (ST/T wave abnormalities). Fifty-seven percent of potential cardiac allografts in this cohort were accepted for transplantation. Left ventricular hypertrophy on ECG was a strong predictor of allograft nonuse. No significant associations were seen among corrected QT interval prolongation, repolarization changes, and allograft use for transplantation after adjusting for donor clinical variables and echocardiographic findings.We have performed the first comprehensive study of ECG findings in potential donors for cardiac transplantation. Many of the common ECG abnormalities seen in organ donors may result from the heightened state of sympathetic activation that occurs after brain stem herniation and are not associated with allograft use for transplantation.